Late 1931 Cast Iron Rear Brake Drum

[Ford1931]

I have a late rear cast iron brake drum that is 11 inches plus 3/32 which is .093 oversize. Is this still a useable drum. It is smooth and does not need turning. The other one I have is a perfect 11 inches. Can I use the two on the same car if I arc new linings.

[1931 flamingo]

I believe most states limit is .060 over. I also believe there is more "meat" on the late 31's. Your car, your choice. Make sure you've got good insurance.
Paul in CT JMO

[Tom Wesenberg]

I'd use them and both on the same car should be fine.
When I worked at the GM dealership in the 70's the limit was .090".

BTW, the local parts stores counterman's job is to sell parts, so to him a like new disc or drum is beyond turning.

[Kurt in NJ]

Originally Posted by 1931 flamingo

I believe most states limit is .060 over. I also believe there is more "meat" on the late 31's. Your car, your choice. Make sure you've got good insurance.
Paul in CT JMO

from Wisconsin gov site for motor vehicle--
"Linings, pads, drums and rotors that all meet manufacturer's minimum recommendations Linings, pads, drums and rotors that all meet manufacturer's minimum recommendations"

the specs from the service bulletins--page 514 --
"under no circumstances must any attempts be made to turn down brake drums on A cars and AA trucks"

It varies by state, some have no spec, some revert to manufactures spec, some .090 is good, some you can be arrested for intent to sell any brake drum over .060, some say a cracked drum is ok if it is banded.
The commonly quoted .060 is in the minority from the searching I have done.
In some states the new cast iron drums are not "legal" because they don't have the max oversize marked (the markings were mandated after 1971 for all new drums)

In NJ it is manufactures specs if the drum is made before 1971 and not marked

[Richard in Anaheim CA]

It is generally not recommended to use two drums so much different in size on the same axle.

They will expand and contract at different rates and cause uneven braking.

I have only heard of cast iron FRONT drums in '31, never REAR cast iron REAR drums.

[larrys40]

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Ford31,

The original later '31 cast iron drums are excellent drums... and for those who say they've never seen them.... that's because they are very hard to come by... They can be identified by a protruding ridge that instead of smooth like the steel drums.
I would agree that I would prefer my drums to be a little more equal in oversize.. It is useable but it is definitely at the upper limit of what I would use... You may need oversize linings on that wheel. If you do that just make sure you use like linings ( woven). and arc the drums, use a centering gauge to ensure they are centered on the backing plate to drum contact. Chamfer the leading/trailing edge on the shoes....

If you can obtain original cast irons they are great! If not go with the new cast drums... mounting properly/ and yes, they will need to be turned to true as well.
If you use oversize on a particular wheel it is a good idea to mark the inside of the drum so noting ... so that if yourself or someone else is in to it at some time and point they have a heads up.

Larry Shepard